This proposed research extends work previously done by the principal investigator (Lust, 1974) on children's first language acquisition of English into another language: Japanese. Acquisition studies planned in this language are motivated theoretically by and modelled methodologically on the previous work in English. The work centers on the structure of coordination in child language. The previous work isolated grammatical (syntactic) factors which appeared to interact with a putative cognitive-perceptual principle of language acquisition, i.e., the preference for nonelimination of redundancy in child language. Mainly, directionality of syntactic deletion was found to interact with this preference in coordinate structures; and the preference itself in this case was explained by the grammatical structure of conjunction in natural language. Experiments planned for Japanese are intended 1) to assess the "universal" nature of these effects in language acquisition by children and 2) to further analyze their nature. Differences in grammatical structure of Japanese as opposed to English provide a principal experimental manipulation for the further study of the grammatical effects found in English acquisition. Methodologically, the experiments use an elicited imitation task in correlation with speech sample analysis with young children (two- and three-year olds).